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Does The Rivian R1T Have A “Rapidgate” Issue?

If you’ve followed my articles, you might remember the problems I’ve had with the 2018 Nissan LEAF I used to own. Living in Phoenix at the time I bought it, the vehicle would overheat just driving down the freeway in the summer temperatures there. Even in cooler temperatures in the fall and winter, the battery would still overheat during DC fast charging sessions, making for road trips that are painfully slow.

Even with software updates, my last attempt to take a short road trip in the vehicle was painfully long, with two-hour charging stops as charging rates plummeted. Once again, heat buildup on repeated charging stops would kill charging speeds, largely because the LEAF had no cooling system.

You’d think that charging problems like this would be completely solved by liquid cooling systems, but a recent video at the Out of Spec Reviews YouTube channel shows us that this isn’t always the case.

In the video, Kyle Conner tells us about some of the thermal management problems he’s come across testing his Rivian R1T pickup truck. While he’s recently spent a lot of time talking about problems with charging infrastructure (especially reliability of Electrify America stations), this time, he’s having problems with the truck.

He points out that he’s had problems with the truck in the summer, but he waited to see how it performed in winter, and sadly, it’s still building up too much heat and charging more slowly than it usually does.

He starts out pointing out that in many cases, slower charging than you should get is often caused by other drivers. At most Electrify America stations, people with slow-charging cars like the Kia Niro or Chevy Bolt often plug their car in at a 350 kW stall when slower 150 kW stalls are available. When people who pull up to the station with a car capable of faster charging pull up, they’re left with the slower stalls.

So, kids, don’t do that! If you’ve got a slower car (like I do), charge in the slower stalls. Leave the faster stalls for the people who can actually get the most from them.

Back on the topic at hand, he points out that not all cooling problems are caused by the same issues. Sometimes, it’s the electric motor or power inverter that heats up. In his case, he has managed to overheat the Rivian inverters on steep downhill segments with a heavy trailer. When the inverter overheats, it shuts off the regenerative braking, which can be somewhat dangerous as it’s not a good idea to manage downhill segments with just friction brakes (because they, too, can overheat).

When it comes to charging, the Rivian can get as much as about 220 kW charging rates, but he then explains that there are two ways to get an EV to not achieve its best charging.

One thing you can do is drive the crap out of it. Racing, lots of hard acceleration and braking, and other hard driving cycles (like mountain towing) can cause a lot of heat buildup that thermal management systems can struggle to keep cool, or fail to keep cool. To prevent damage or fire, the car eventually cuts back how much power it can deliver — or charge. This is usually an inverter or motor issue, but batteries can overheat eventually.

An inverter or motor doesn’t have a lot of thermal mass, so they should be able to cool off fairly quickly once they’re not asked to work so hard. But, batteries are another thing entirely. Once heat builds up in them, it can take an overworked or inadequate cooling system some time to remove the heat. The problem is, if you’re highway driving, you go straight from driving fast to the charging station, and you arrive with a battery that’s already too hot.

So, the car throttles charging speeds back to protect the battery from damage or unplanned internal combustion. In the case of the Rivian, he’s seeing it throttle charging speeds that should exceed 200 kW get cut back to as little as 90 kW. And, this can happen in winter temperatures — in Colorado!

The battery charging speed doesn’t start out slow, but after a few minutes of charging it drops speeds, showing that heat had built up during the charge and exceeded the allowable temperatures for maximum charging speeds. He figures that the vehicle probably isn’t running the cooling system as aggressively as it could early in the charge or when pulling up to stations.

What He Thinks Rivian Could Do To Fix This Problem Without Rebuilding Battery Packs

He thinks that the battery pack probably has a few cells that aren’t getting as good a cooling as the rest of them. It’s a big, complex “double stack” battery pack, and there’s probably some corner of the pack that’s getting hot first. But, they could possibly allow the maximum temperature to higher (which may be risky) or pre-cool the pack more aggressively to try to get ahead of the portion of the pack that’s getting too hot first. Some mix of the two is possible, too.

For now, it might not be a good idea to not precondition the battery for the first charging stop on a road trip with a Rivian in winter. Future software updates could fix this.

Rivian Has Made It Tougher To Gather Data On This

In the past, Rivian vehicles had a secret menu where you could get all of the vehicle’s data, including things temperature sensors for different parts. But, with a software update, the secret menu and app disappeared. Owners knew in the past that the vehicles wouldn’t go above 45 degrees (C), which is pretty aggressive cooling. But, they can no longer get those figures.

We’re Still In The Early Days of EVs

One thing to keep in mind is that we’re still in the early days of EVs. Some manufacturers will have more problems than others, and some (especially Tesla and to some extent GM) have a lot more experience than others. Every manufacturer is going to have to figure out the best way to cool their designs, and eventually general knowledge of how to best do cooling will become the norm.

Featured image provided by Rivian.

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Written By

Jennifer Sensiba is a long time efficient vehicle enthusiast, writer, and photographer. She grew up around a transmission shop, and has been experimenting with vehicle efficiency since she was 16 and drove a Pontiac Fiero. She likes to get off the beaten path in her "Bolt EAV" and any other EVs she can get behind the wheel or handlebars of with her wife and kids. You can find her on Twitter here, Facebook here, and YouTube here.


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